Swift waitUntilAllTasksAreFinished error

http://stackoverflow.com/questions/26947608/waituntilalltasksarefinished-error-swift

func checkLogin(succeed: Bool, msg: String) {
    if (succeed) {

        NSOperationQueue.mainQueue().addOperationWithBlock {
            self.performSegueWithIdentifier("logInTrue", sender: self)
        }        

    }
}